Any collection of dice can, in principle, constitute a dice set but the typical usage of the phrase refers to a collection of seven polyhedral dice. It's a set of a d4, d6, d8, d10, d12, d20, and a d%. These include five dice of the platonic solids and two ten sided dice; one marked for the ones and the other marked for the tens. All of the dice are marked with numerals rather than pips. This exact set was popularized by some of the earliest Dungeons & Dragons supplements and through a mixture of flexibility and inertia has remained the default set for nearly ever RPG that bothers with multiple dice types.
If you type dice set into a search engine I'd estimate at least 90% of the products that come up will be seven dice sets. The recent increase in the popularity of table top role playing games brought in by the popularization of nerd culture has led to an explosion of volume and variety of dice sets. This isn't really surprising since RPG nerds are generally inclined towards DIY, artsy, bespoke items and the Etsy crowd are drawn into the table top spaces by its increased presence in new media. The increasing overlap has created an extremely diverse market. Dice made of copper, bone, titanium, glass, semiprecious gem stone, and more patterns of plastic than you can imagine are now available at a variety of prices. Dice sets as over priced nerd status symbol art items is a weird but not wholly inexplicable turn that seems to be happening.
If you find yourself wanting a dice set for what ever reason there are a handful of considerations. Cost is the first, dice set start at around five dollars and run up to a hundred times that. How do they feel in your hands? It's a small thing but dice are intrinsically tactile and heavier dice with sharper edges typically feel better to me. If you don't care at all then you might consider a phone app instead of an actual set. Legibility, can you read the font easily in most lighting conditions? If you have vision problems this can be especially important but regardless poor contrasts between the numerals and the body of the dice are often a cause of frustration. Lastly is the aesthetics, do you like the way they look? Monochrome, speckled, marbled, transparent, glow in the dark, you've got options. There's something oddly satisfying about a set of small colored shapes that capture a mood. I'm not going to claim that dice say a lot about a role player but with the range of options available it's bound to say something.
IRON NODER XIV: THE RETURN OF THE IRON NODER